Hydrofracturing, also known as “hydrofracing”, “hydraulic fracturing”, and/or “fracting”, involves pumping a mixture of water and proppants into a section of a geological formation with sufficient pressure to crack and/or open natural fractures within the formation. The proppants are used to “prop” open the cracks and/or natural fractures so that pressure from the geological formation does not close the cracks and/or fractures and reduce or shut off, for example natural gas, from the formation.
High quality proppants, for example spherical shaped proppants from high grade Brady and Ottawa sands or sintered aluminosilicates obtained from high purity grade bauxite and kaolin, can afford up to 30 to 50 percent more oil and/or gas from a geological formation compared to the use of low grade proppants or no proppants at all. However, high grade Brady and Ottawa sands are being depleted and the majority of bauxite deposits are located in China, thereby having a significant shipping cost associated therewith when used in the United States.
In addition to the above, discovery of an estimated 500 trillion cubic feet of natural gas within the Marcellus Shale in 2008 has further increased the potential demand for proppants that can be used for natural gas drilling that employs hydrofracing. Therefore, a process that provides a cost-effective proppant from readily available material would be desirable.